Shaft for medical catheters

ABSTRACT

Several improvements are provided in the design of a catheter shaft to reduce costs and improve performance. In one aspect, a small notch is fabricated into a catheter tube by a nonlaser process such as electric discharge machining (EDM) or mechanical grinding. This notch in the catheter tube is necessary for fluid communication between the catheter lumen and a balloon or other element in communication with the tube. Use of a nonlaser process reduces the costs of fabrication while ensuring a high degree of structure integrity. In another aspect, a method is provided to produce a nonuniform polymer coating on a catheter shaft to reduce friction and to maintain a catheter with a low profile. In another aspect, the catheter is provided with a radiopaque marker which is more visible and is more effective at identifying the location of a balloon. The marker is moved closer to a distal balloon by placing it within an adhesive taper adjacent the balloon.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to surgical device designand fabrication and, more particularly, to a shaft for medicalcatheters.

[0003] 2. Background of the Invention

[0004] Medical catheters, such as balloon catheters, have been provenefficacious in treating a wide variety of blood vessel disorders.Moreover, these types of catheters have permitted clinicians to treatdisorders with minimally invasive procedures that, in the past, wouldhave required complex and perhaps life threatening surgeries. Forexample, balloon angioplasty is now a common procedure to alleviatestenotic lesions (i.e., clogged arteries) in blood vessels, therebyreducing the need for heart bypass operations.

[0005] Previously known catheters are of complex construction, requiringexpensive manufacturing steps and construction of great precision tonavigate the tortuous pathways of a vessel network. For instance, when acatheter provides inflation fluid to a balloon, a small notch istypically provided in the catheter tube to allow fluid to pass from alumen within the tube to the balloon. The conventional method formanufacturing this notch is with a laser, which is expensive and oftencannot be done in-house. Further, use of a laser creates a heat-affectedzone which can lead to fracture of the notch. Moreover, the heat fromthe laser may cause deformation of the material. This is especiallyproblematic when a straight catheter made of a nickel-titanium alloy isdesired. Because the properties of NiTi alloys are extremely temperaturesensitive, laser notching may cause buckling or unwanted curvature inthe material. Accordingly, there is a need for a notch-forming processwhich will not cause damage to the material.

[0006] Further, profile is often a concern for catheters because of thesmall space in which the catheters will be inserted. In addition,because catheters must be passed through a tortuous blood vessel networkto reach the intended treatment site, it is desirable that the cathetersbe substantially frictionless to reduce harmful contact with bloodvessel walls. Catheters therefore are generally provided with a coatingthat will increase lubricity of the catheter. These coatings addadditional, undesired size to the catheter. Thus, there is a need for asubstantially frictionless catheter surface which does not addsignificant profile to a catheter tube.

[0007] In navigating the pathways of a vessel network, a radiopaquemarker is often necessary to identify a specified location on thecatheter. Such markers are typically placed on the catheter tube nearthe location of a distal balloon. However, in medical devices employingaspiration catheters and the like, visibility problems often arise withsuch markers because they are typically made small in order to allow theaspiration catheter to be passed over the marker as it extends towardsthe distal balloon. Accordingly, there is a need for balloon cathetershaving markers which can better identify the location of a balloon whileinside a blood vessel.

SUMMARY OF THE INVENTION

[0008] The present invention addresses the needs raised above byproviding several improvements in the design of a shaft for medicalcatheters. In one aspect, a small notch is fabricated into a cathetertube by a nonlaser process such as electric discharge machining (EDM) ormechanical grinding. This notch in the catheter tube is necessary forfluid communication between the catheter lumen and a balloon or otherelement in communication with the tube. Use of a nonlaser processreduces the costs of fabrication while ensuring a high degree ofstructural integrity.

[0009] In another aspect of the present invention, a method is providedto produce a thinner coating on a catheter shaft to reduce friction withvessel walls. To maintain a surface with a low friction coefficientwhile keeping the profile of the catheter low, the catheter is sputtercoated with Teflon or similar material to produce a nonuniform coating.This nonuniform coating may extend 360 degrees around the catheter tube,and may even provide a coating of less than 360 degrees while stillmaintaining good lubricity.

[0010] In yet another aspect, a catheter wire or tube is provided with aradiopaque marker which is more visible and is more effective atidentifying the location of a balloon on the catheter. The marker ismoved closer to a distal balloon by placing it within an adhesive taperadjacent the balloon. By placing the marker in the taper, the marker canbe made larger and more visible without obstructing the placement of anaspiration catheter or other type of catheter over the catheter wire ortube. Specifically, the marker in being placed inside the taper andcloser to the balloon can act as a stopper to the aspiration catheterand prevent damage to the balloon.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a side view of the catheter of the present invention.

[0012]FIG. 2 is a longitudinal cross-sectional view of the distal end ofa catheter having the improvements of the present invention.

[0013]FIG. 3 is an enlarged cross-sectional view along area 3-3 of FIG.2.

[0014]FIG. 4A is a cross-sectional view along line 4-4 of FIG. 1 showinga nonuniform coating on the catheter.

[0015]FIG. 4B is a cross-sectional view along line 4-4 of FIG. 1 showingan alternate embodiment of a nonuniform coating on the catheter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Referring to FIG. 1, there is depicted a catheter 10incorporating the improvements of the present invention. Although theimprovements of the present invention are depicted and discussed in thecontext of being part of a simple occlusive device having a singlelumen, it should be appreciated that the present invention is applicableto more complex occlusive devices having structures and functionalitiesnot discussed herein. For example, the present inventors contemplatethat the improvements of the present invention may be used in occlusivedevices functioning as anchorable guide wires or filters. In addition,the improvements of the present invention are also applicable tocatheters having other types of balloons, such as latex or silicone, orto catheters having dilatation balloons, made of materials such aspolyethylene terephthalate. Moreover, the improvements of the presentinvention may also be adapted to other types of catheters used in drugdelivery or radiation therapy, such as irrigation catheters, and tocatheters having no balloon at all. The manner of adapting theimprovements of the present invention to these various structures andfunctionalities will become readily apparent to those of skill in theart in view of the description which follows.

[0017] In FIG. 1, an occlusion balloon catheter 10 is shown. Catheter 10generally comprises an elongate flexible shaft or tubular body 12extending between a proximal control end 14, corresponding to a proximalsection of tubular body 12, and a distal functional end 16,corresponding to a distal section of tubular body 12. Tubular body 12has a central lumen 18 which extends between ends 14 and 16. Aninflation port 20 is provided on tubular body 12 near the proximal end14. Inflation port 20 is in fluid communication with lumen 18, such thatfluid passing through inflation port 20 into or out of lumen 18 may beused to inflate or deflate inflation balloons in communication withlumen 18. Lumen 18 is sealed fluid tight at distal end 16. Inflationport 20 may be similar to existing female luer lock adapters or would bea removable valve at the end, as disclosed in assignee's co-pendingapplication entitled LOW PROFILE CATHETER VALVE AND INFLATION ADAPTER,application Ser. No. 08/975,723 filed Nov. 20, 1997, the entirety ofwhich is incorporated by reference.

[0018] The length of tubular body 12 may be varied considerablydepending upon the desired application. For example, where catheter 10serves as a guidewire for other catheters in a conventional percutaneoustransluminal coronary angioplasty procedure involving femoral arteryaccess, tubular body 12 is comprised of a hollow hypotube having alength in the range of from about 160 to about 320 centimeters with alength of about 180 centimeters being optimal for a single operatordevice and 300 centimeters for over the wire applications. Alternately,for a different treatment procedure, not requiring as long a length oftubular body 12, shorter lengths of tubular body 12 may be provided.Moreover, the catheter 10 may comprise a solid shaft rather than ahollow hypotube.

[0019] Tubular body 12 generally has a circular cross-sectionalconfiguration with an outer diameter within the range of from about0.008 inches to 0.14 inches. In many applications where catheter 10 isto be used as a guidewire for other catheters, the outer diameter oftubular body 12 ranges from 0.010 inches to 0.038 inches, and preferablyis about 0.014 to 0.018 inches in outer diameter or smaller. Noncircularcross-sectional configurations of lumen 18 can also be adapted for usewith the present invention. For example, triangular, rectangular, oval,and other noncircular cross-sectional configurations are also easilyincorporated for use with the present invention, as will be appreciatedby those of skill in the art.

[0020] Tubular body 12 has sufficient structural integrity, or“pushability,” to permit catheter 10 to be advanced through vasculatureto distal arterial locations without buckling or undesirable kinking oftubular body 12. It is also desirable for tubular body 12 to have theability to transmit torque, such as in those embodiments where it may bedesirable to rotate tubular body 12 after insertion into a patient. Avariety of biocompatible materials, known by those of skill in the artto possess these properties and to be suitable for catheter manufacture,may be used to produce tubular body 12. For example, tubular body 12 maybe made of stainless steel such as Elgiloy (TM), or may be made ofpolymeric materials such as nylon, polyimide, polyamides, polyethyleneor combinations thereof. In one preferred embodiment, the desiredproperties of structural integrity and torque transmission are achievedby forming tubular body 12 out of an alloy of titanium and nickel,commonly referred to as nitinol. In a preferred embodiment, the nitinolalloy used to form tubular body 12 is comprised of about 50.8% nickeland the balance titanium, which is sold under the trade name Tinel (TM)by Memry Corporation. It has been found that a catheter tubular bodyhaving this composition of nickel and titanium exhibits an improvedcombination of flexibility and kink resistance in comparison to othermaterials. Further details are disclosed in assignee's co-pendingapplications entitled HOLLOW MEDICAL WIRES AND METHODS OF CONSTRUCTINGSAME, application Ser. No. 08/812,876, filed on Mar. 6, 1997, CATHETERBALLOON CORE WIRE, application Ser. No. 08/813,024, filed Mar. 6, 1997,and CORE WIRE WITH SHAPEABLE TIP (Attorney Docket PERCUS.053A),application Ser. No. ______, filed on the same date herewith, all ofwhich are hereby incorporated by reference in their entirety.

[0021] As illustrated in FIG. 1, an expandable member such as aninflatable balloon 22 is mounted on tubular body 12. Balloon 22 may besecured to tubular body 12 by any means known to those skilled in theart, such as adhesives or heat bonding. In one preferred embodiment,balloon 22 is a compliant balloon formed out of a material comprising ablock polymer of styrene-ethylene-butylene-styrene (SEBS). As shown inFIGS. 2 and 3, balloon 22 has a proximal end 24 and a distal end 26which are both secured to the outer surface of tubular body 12. Balloon22 may be secured to the tubular body 12 by any means known to those ofskill in the art, such as adhesives or heat bonding. FIGS. 2 and 3 showthe use of adhesives 28 bonding the balloon at its proximal end 24 anddistal end 26, respectively, up to adhesive stops 32 and 34, thedistance between the adhesive stops defining the working length of theballoon. Further details are disclosed in assignee's co-pendingapplication entitled BALLOON CATHETER AND METHOD OF MANUFACTURE(Attorney Docket PERCUS.010CP1), application Ser. No. ______, filed onthe same date herewith, the entirety of which is hereby incorporated byreference.

[0022] A notch 36 is provided in the tubular body 12, as shown on theback side of tubular body 12 in FIG. 2, within the working length of theballoon to provide fluid communication between the lumen 18 and theballoon 22. A core wire 38 is provided at the distal end of the tubularbody 12, inserted into the lumen 18 so that part of the core wire 38 isvisible through the notch 36. Coil 40 surrounds the core wire 38 and issoldered at a distal end into a rounded tip 42. The core wire 38 issecured within the lumen 18 of tubular body 12 by a combination ofadhesive bonding and crimping at points 44 and 46 of the tubular body12. Tapers 48 and 50 are shown at the proximal and distal ends of theballoon 22, respectively. A radiopaque marker 52 is located within theproximal taper 48.

[0023] The core wire 38 and the coil 40 are formed into a subassemblyprior to attachment to tubular body 12. Once the coil 40 is attached tothe core wire, a proximal end of core wire 38 is inserted into tubularbody 12 at distal end 54. Two crimps 44 and 46 are provided near thedistal end 54 of the tubular body 12 to secure the core wire 38 to thetubular body. The crimps are preferably located in a location betweenthe notch 36 and the distal end 54 of the tubular body 12. The crimpsare preferably located a distance 0.5 to 1.5 mm apart, and morepreferably, about 1.0 mm apart. The more distal crimp 46 preferably islocated about 0.5 mm from the distal end 54 of tubular body 12. Furtherdetails are disclosed in the above-referenced application CORE WIRE WITHSHAPEABLE TIP (Attorney Docket PERCUS.053A), application Ser. No.______, filed on the same date herewith.

Fabrication of the Notch

[0024] In one aspect of the present invention, the notch 36 shown inFIG. 2 is formed by a nonlaser process. Preferably, the process used iselectric discharge machining (EDM). This method allows removal of metalby a series of rapidly recurring electrical discharges between anelectrode (the cutting tool) and the workpiece in the presence of aliquid (usually hydrocarbon dielectric). Using EDM, the notch 36 can bemade economically but also with great precision. The notch 36 preferablyhas a length between 0.001 and 0.005 inches and a width between 0.001and 0.005 inches, depending on the working length of the balloon 22 andthe diameter of the tubular body 12. As shown in FIG. 2, when thedistance between the inner surfaces of the adhesive stops 32 and 34 is 4mm and the outer diameter of the tubular body 12 is 0.0132 inches, thenotch 36 preferably has a length of 1.5 mm and a width of 0.003 inches.The notch 36 may be centered within the working length of the balloon,such that the distance between the ends of the notch and each of theadhesive stops 32 and 34 is the same. Alternatively, when the core wire38 extends into the lumen 18 of the tubular body 12 and is visible inthe notch 36, the location of the notch 36 may be shifted towards distalend 54 of the tubular body. In FIG. 2, where the distance betweenadhesive stops 32 and 34 is 4 mm, the core wire 38 extends 0.5 mm intothe notch 36. The notch 36 is 1.5 mm long, with the proximal end 56 ofthe notch 36 located a distance 1.5 mm from the first adhesive stop 32,and the distal end 58 of the notch 36 located 1 mm from the secondadhesive stop 34.

[0025] To manufacture the notch, preferably, an EDM with a 0.0055±0.0005inch electrode is used. A current of 0.5 amps is applied, with an ontime of 6 seconds and an off time of 50 seconds. Although the EDMprocessing of the notch has been described with respect to specificparameters, it should be recognized that other parameters as well may beused for the EDM. Furthermore, EDM may be used not only for fabricationof a distal notch to inflate a balloon, but also for a notch such asinflation port 20 at the proximal end of the tubular body as shown inFIG. 1, or other types of notches that may be provided for a medicalcatheter.

[0026] Although fabrication of the notch has been described withreference to an EDM procedure, other nonlaser processes may be used aswell. For instance, mechanical grinding is another low cost procedurefor fabricating a notch that can be performed in-house.

Nonuniform Coating

[0027] In another aspect of the present invention, the shaft or tubularbody 12 is sputter-coated with a polymeric material to reduce frictionbetween the catheter and blood vessels and produce a lubricious,nonuniform coating on the tubular body 12. As used herein, “nonuniform”refers either to a coating that is variable in thickness along thecircumference or length of the body 12, or to a coating which covers thebody 12 in some areas but not at all in others. As shown in FIG. 1, acoating 60 is applied to the tubular body 12 between a proximal marker62 and the balloon 22. The coating begins at a distance preferablywithin about 5 mm of the marker 62, and more preferably within about 2mm. The coating 60 terminates preferably within about 1 cm of theproximal taper 48. Preferred coating materials includepolytetrafluoroethylene (TFE), with Teflon being a desired material forthe coating 60. Those skilled in the art will recognize that similarmaterials with high lubricity may be used.

[0028] As shown in FIGS. 4A and 4B, a nonuniform coating 60 adds verylittle dimension to the tubular body 12. FIG. 4A shows one embodimentwhere the coating 60 is thin with a variable thickness that coverssubstantially the entire circumference of the tubular body 12. FIG. 4Bshows another embodiment where the coating 60 is thin but does not coatthe entire circumference of tubular body 12. Thicknesses in the range ofabout 0.001 to about 0.0035 inches are preferred. In both of theembodiments shown in FIGS. 4A and 4B, preferably, the coating 60 has athickness of no greater than about 0.01 inches, and more preferably, thecoating thickness is no greater than about 0.0035 inches. Thus, it hasbeen discovered that sufficient lubricity can be achieved with anonuniform or even intermittent, sporadic coating, while simultaneouslymaintaining a low profile.

[0029] To apply the polymeric coating 60 to the tubular body 12, thesurface of the tubular body 12 is first cleaned. Preferable cleaningmethods are by preparing a cleaning solvent blend using a 1:1 (byvolume) mixture of acetone and isopropyl alcohol. The tubular body 12may be cleaned by wiping the body with a lint-free towel or cloth wettedby this solvent blend. After the solvent wipe, the tubular body 12 isheat cleaned in an oven for 15 minutes at 540° F.

[0030] The Teflon coating solution may be Xylan 1006/870 Black Tefloncoating as obtained from Whitford Corporation. To achieve a thinner filmthickness, the coating can be mixed with a thinner such as thinner #99Bfrom Whitford Corporation. To mix the coating solution with the thinner,the coating solution is first mixed well in a container using amechanical stirrer for about 5 to 10 minutes to remove residue andTeflon particles from the bottom of the container. About 80 parts byvolume of the coating solution is mixed with about 20 parts by volume ofthe thinner with a mechanical stirrer until the blend is uniform toachieve 0.0035 inch thickness. This blend is filtered using a cone typecoarser filter paper to remove lumps. After completing these steps, thecoating solution is ready to spray.

[0031] The coating is produced on the tubular body by a spray gun,preferably with an agitating pressure pot, although a spray gun withoutan agitating pressure pot may be used. The spraying process of thepresent invention preferably produces a nonuniform Teflon coating 360degrees around the tubular body and extending continuously along thelength of the tubular body 12. When applying the coating with the spraygun, rather than pulling the trigger all the way and holding itcontinuously, the trigger can be selectively depressed and released, ordepressed with various degrees of pressure, as the gun passes from leftto right over a portion of the tubular body. This process is repeated asthe tubular body is rotated and a coating is applied 360 degrees aroundthe tubular body. Coating on the tubular body by the spray gun can alsobe adjusted by controlling the flow rate of the spray exiting the gun.Moreover, the motion of the gun over the body allows control of thethickness and uniformity of the coating. These factors allow the coating60 to be a thin, nonuniform coating covering substantially all of thetubular body, as shown in FIG. 4A.

[0032] Alternatively, the profile of the catheter can be reduced evenfurther by spraying less than 360 degrees around the tubular body 12, asshown in FIG. 4B. The nonuniformity of the coating, thus, results fromthe tubular body 12 having portions that are coated with the polymer andother portions having no coating at all. The degree of nonuniformitydepends on how the trigger of the spray gun is selectively activated anddeactivated. Other methods to produce nonuniformity on the tubular body12, such as masking portions of tubular body 12, may also be used.Moreover, the nonuniformity may result from the coating not beingsprayed continuously over the circumference and/or length of the body.

[0033] After spraying, the coating should be flashed off to avoid anyblistering. The coated tubular bodies are flashed off in an oven at 200°F. for 15 minutes. Then, the tubular body is cured. When a NiTi materialis used for the tubular body, a curing temperature of about 540° F. isused in order to maintain the heat treated superelastic properties ofNiTi. The curing step takes about one-half hour. After allowing thecoated tubular bodies to cool, parts of the tubular body may be strippedto remove the coating from undesired areas. For instance, at thelocation of the proximal marker 62 shown in FIG. 1, no coating isdesired. Suitable means for stripping include an abrasive and a razorblade, as well as other stripping means known to those skilled in theart.

Distal Marker

[0034] In another aspect of the present invention, a tubular marker 52,as shown in FIG. 2, is located within an adhesive taper 48 adjacent theballoon 22. Although the marker 52 is shown in the form of a tube, itwill be appreciated by those skilled in the art that markers of othershapes may be used as well. To place the marker 52 within the taper 48,the marker is first slid over the coil 40 and core wire 38 and over thedistal tip of the tubular body 12 past the inflation notch 36 so that itis out of the way for balloon bonding. Adhesive stops 32 and 34 and theballoon 22 are then mounted to the tubular body 12 using adhesives orother means known to those skilled in the art. One preferred method formounting the adhesive stops and balloon to the tubular body is describedin the above-referenced application BALLOON CATHETER AND METHOD OFMANUFACTURE (Attorney Docket PERCUS.010CP1), application Ser. No.______, filed on the same day as the present application.

[0035] After balloon bonding, the marker 52 is slid towards the balloon22 such that it is between about 0.5 and 3 mm from the proximal end ofthe balloon. More preferably, the marker 52 is located within about 1.0mm from the proximal end 24 of the balloon 22. In the preferredembodiment shown in FIG. 2, the marker 52 is located about 0.75 mm fromthe balloon. The gap between the balloon 22 and the marker 52 is filledwith an adhesive material taper 48. Preferably, a cyanoacrylate adhesivesuch as LOCTITE 4011 is used. However, as will be appreciated by thoseof skill in the art, other adhesives may be used. The taper 48 alsoextends from the proximal end 64 of the marker to point 66 on thetubular body 12, as well as from the proximal end 24 of balloon 22 toproximal end 64 of marker 52.

[0036] Because the marker is placed within the adhesive taper 48 of theballoon 22, the marker can be made larger and closer to the balloon,thereby increasing visibility without obstructing advancement of anaspiration catheter or the like when the tubular body 12 is used as aguidewire. Further details regarding an aspiration catheter aredisclosed in assignee's co-pending application entitled ASPIRATIONCATHETER, application Ser. No. 08/813,308, filed Mar. 6, 1997, theentirety of which is hereby incorporated by reference. The markerpreferably has an outer diameter of at least about 0.02 inches. Morepreferably, the marker 52 has an inner diameter of about 0.017 inchesand an outer diameter of about 0.024 inches. The proximal cyanoacrylateballoon taper 48 is preferably about 4 mm long, extending from point 24on the balloon 22 to point 66 on the tubular body. The marker taper,extending from point 24 to distal point 68 on marker 52, is preferablyabout 0.75 mm long.

[0037] It will be appreciated that certain variations of the shaft ofthe present invention may suggest themselves to those skilled in theart. The foregoing detailed description is to be clearly understood asgiven by way of illustration, the spirit and scope of this inventionbeing limited solely by the appended claims.

What is claimed is:
 1. A catheter, comprising: a tubular body havingproximal and distal sections, the tubular body having a lumen extendingtherethrough; an expandable member with an interior volume mounted onthe distal section of the tubular body, the expandable member havingproximal and distal ends; a notch formed by electric discharge machiningin the tubular body for providing fluid communication between the lumenand the interior volume of the expandable member; a nonuniform polymercoating formed on at least a portion of the tubular body to provide asubstantially frictionless surface; a marker mounted on the distalsection of the tubular body adjacent the proximal end of the expandablemember; and a taper formed from the proximal end of the expandablemember and covering the distal marker.
 2. A catheter, comprising: atubular body having proximal and distal sections, the tubular bodyhaving a lumen extending therethrough; and a notch formed by electricdischarge machining in the tubular body.
 3. The catheter of claim 2 ,further comprising an expandable member with an interior volume mountedon the distal section of the tubular body, wherein the notch providesfluid communication between the lumen and the interior volume of theexpandable member.
 4. The catheter of claim 3 , wherein the notch has alength of about 1.5 mm and a width of about 0.003 inches.
 5. A notch fora catheter body formed by electric discharge machining.
 6. A method ofmanufacturing a notch in a catheter body, comprising the step ofelectric discharge machining at least a portion of the catheter body. 7.A catheter, comprising: a tubular body having proximal and distalsections, the tubular body having a lumen extending therethrough; and anotch formed by mechanical grinding of the tubular body.
 8. The catheterof claim 7 , further comprising an expandable member with an interiorvolume mounted on the distal section of the tubular body, wherein thenotch provides fluid communication between the lumen and the interiorvolume of the expandable member.
 9. The catheter of claim 8 , whereinthe notch has a length of about 1.5 mm and a width of about 0.003inches.
 10. A notch for a catheter body formed by mechanical grinding.11. A method of manufacturing a notch in a catheter body comprising thestep of mechanically grinding at least a portion of the catheter body.12. A catheter, comprising: an elongate shaft; a nonuniform polymercoating formed onto at least a portion of the shaft to provide asubstantially frictionless surface.
 13. The catheter of claim 12 ,wherein the nonuniform polymer coating is produced by sputter coating.14. The catheter of claim 12 , wherein the nonuniform coating isproduced by selectively spraying a polymer coating onto the shaft. 15.The catheter of claim 12 , wherein the elongate shaft is substantiallycylindrical.
 16. The catheter of claim 13 , wherein the nonuniformcoating formed onto at least a portion of the shaft provides a coatingsubstantially 360 degrees around the shaft.
 17. The catheter of claim 13, wherein the nonuniform coating formed onto at least a portion of theshaft provides a coating less than 360 degrees around the shaft.
 18. Thecatheter of claim 12 , wherein the nonuniform coating is formed bycoating the shaft with a polymer coating of varying thickness.
 19. Thecatheter of claim 12 , wherein the nonuniform coating is formed byproviding coated and uncoated portions on the shaft.
 20. The catheter ofclaim 12 , wherein the polymer coating is made of apolytetrafluoroethylene.
 21. A method of lubricating a catheter shaft,comprising the step of coating the catheter shaft with a polymericmaterial to form a nonuniform coating on the catheter shaft.
 22. Themethod of claim 21 , wherein the step of coating comprises selectivelyspraying the polymeric material onto the shaft.
 23. The method of claim21 , wherein the step of coating comprises sputter coating the polymericmaterial onto the shaft.
 24. The method of claim 21 , wherein the stepof coating produces a nonuniform coating of varying degrees ofthickness.
 25. The method of claim 21 , wherein the step of coatingproduces a nonuniform coating on the shaft wherein coated and uncoatedportions are provided on the shaft.
 26. A method of reducing the profileof a medical catheter, comprising the step of producing a nonuniformcoating on the catheter.
 27. The catheter of claim 26 , wherein thenonuniform coating is formed by coating the catheter with a polymercoating of varying thickness.
 28. The catheter of claim 26 , wherein thenonuniform coating is formed by providing coated and uncoated portionson the catheter.
 29. The catheter of claim 26 , wherein the coating ismade of a polytetrafluoroethylene.
 30. A catheter, comprising: anelongate body having proximal and distal sections; an expandable membermounted on the distal section of the tubular body, the expandable memberhaving proximal and distal ends; a marker mounted on the distal sectionof the elongate body adjacent the proximal end of the expandable member;and a taper formed from the proximal end of the expandable member in aproximal direction to the elongate body and covering the distal marker.31. The catheter of claim 30 , wherein the marker is a tube.
 32. Thecatheter of claim 30 , wherein the marker is radiopaque.
 33. Thecatheter of claim 30 , wherein the marker is located within about 3 mmof the proximal end of the expandable member.
 34. The catheter of claim30 , wherein the taper is formed from a cyanoacrylate adhesive.
 35. Thecatheter of claim 30 , wherein the marker has an outer diameter of atleast about 0.020 inches.
 36. A method of manufacturing a ballooncatheter having a radiopaque marker, comprising the steps of: providingan elongate body with proximal and distal ends; providing a balloonhaving proximal and distal ends; providing a radiopaque marker; mountingthe balloon over the elongate body so that the balloon is in anappropriate position for balloon bonding; mounting the marker over theelongate body at a position adjacent the proximal end of the balloonforming a gap between the marker and the balloon; and forming a taperfrom the proximal end of the balloon to the elongate body toward theproximal end of the elongate body, the taper filling the gap between theballoon and the marker and covering the marker.
 37. The method of claim36 , wherein the taper is a cyanoacrylate adhesive.
 38. The method ofclaim 36 , wherein the marker is positioned within about 3 mm of theproximal end of the balloon.
 39. A catheter, comprising: an elongateshaft; a radiopaque marker for locating a desired point on the shaft;and an adhesive taper covering the marker.
 40. A method of locating adesired point on a catheter when inserted inside a human body,comprising the steps of: providing an elongate catheter shaft; providinga radiopaque marker located at the desired point on the catheter shaft;and forming a taper covering the marker.